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FEATURE:MINE Magazine – Microscopic curiosities: the business of unearthing new minerals

Discoveries of new mineral samples are rare but in October 2016, after some painstaking work, a US-based physics professor announced the discovery of a new mineral called merelaniite, from the Merelani mining district in Tanzania. So what happens to a mineral post-discovery? Experts provide an insight into the niche world of mineral research, discovery and collecting.

In 2012, John Jaszczak, a professor of physics at Michigan Tech University, was in the process of studying samples of molybdenite from a quarry in Italy using a Raman spectrometer – a light scattering technique, whereby a molecule scatters incident light from a high-intensity laser light source.

Around the same time he came across an article about unusual minerals from the Merelani mining district in Tanzania, written by a 14-year-old girl on an internship with a mineral expert named Mike Wise.

Since the 1960s, Merelani mining district has been well-known for its abundance of the beautiful purple-violet tanzanite rock, named after the country where it was first discovered and is endemic.

Jaszczak noticed the picture of the sample looked very similar to molybdenite, but with unusual cylindrical whiskers not present in the former.

After obtaining a sample of the mineral, further studies led to the discovery that it contained molybdenite and sulphur, as expected, but also lead – and that’s when he knew it was potentially an undiscovered mineral.

Jaszczak ran the Raman spectrum results of the new mineral through the search on the RRUFF database of Raman spectra and it did not match any minerals listed, confirming this discovery.

Discovering the structure of merelaniite

There are 5,179 minerals listed by the International Mineralogical Association, and its Commission on New Minerals, Nomenclature and Classification (CNMNC) receives more than 80 proposals each year for new ones – but passing the requirements is tough.

Most suspected new minerals turnout to be a physical mixture or something that is in a series of compositional ranges that still fit into other ranges, says Professor Kip Jeffrey, head of Camborne School of Mines at the University of Exeter.

“Even at a microscopic scale you can get a physical mixture of two known minerals which if you do a chemical analysis are two minerals mixed together, which gives you a strange pattern but not because it is a new mineral just because it is a physical mix,” he explains.

It would be four years, a series of rigorous mineral chemical and structure tests, utilising a global scientific effort, including Mike Rumsey and John Spratt at the Natural History Museum in London, before the discovery of merelaniite could be announced.